Sector-directional radio beacon for azimuth and elevation angle measuring

ABSTRACT

To provide a rotating radiation pattern in a predetermined sector of + OR - 18* from which a Tacan receiver can determine azimuth and elevation angles, a first antenna which radiates a carrier frequency F is flanked horizontally by a second antenna which radiates a frequency F + 135 Hz. and vertically by a third antenna which radiates a frequency F + 15 Hz. The spacing between said first antenna and said second and third antennas being 5/ pi . lambda , which distance is dependent upon the desired width of said sector.

United States Patent Inventor Klaus Dieter Eckert Ludwigsburg, Germany Appl. No. 804,169

Filed Mar. 4, I969 Patented Oct. 5, 1971 Assignee International Standard Electric Corporation New York, N.Y.

SECTOR-DIRECTIONAL RADIO BEACON FOR AZIMUTII AND ELEVATION ANGLE MEASURING 6 Claims, 1 Drawing Fig.

US. Cl 343/105,

343/106, 343/108 Int. Cl G015 1/30 Field of Search 343/]05,

Elevation [56] References Cited UNITED STATES PATENTS 3,534,366 10/ 1970 Guldenpfennig 343/106 2,727,231 [2/1955 Gaudillere 343/105 Primary Examiner-Rodney D. Bennett, Jr.

Assistant Examiner-Richard E. Berger Attorneys-C. Cornell Remsen, Jr., Walter J. Baum, Percy P.

Lantzy, Philip M. Bolton, Isidore Togut and Charles L. Johnson, Jr.

PAT-ENIl-In om 5am 3,61 1, 384

1 (FHSHZ) Elevation 2% EMF I INVENT OR KLAUS- 0/6 TER ECKE'R T m, m w

ATTORNEY SECTOR-DIRECTIONAL RADIO BEACON FOR AZIMUTH AND ELEVATION ANGLE MEASURING BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a mobile directional beacon, and in particular to one which provides rotating radiation patterns in a predetermined sector.

2. Description of Prior Art In order to provide sector radio beacons compatible with Tacan receivers, transmitting systems have been suitably designed such that at the receiving end, a Hz. as well as a 135 Hz. modulation component is available. This has been achieved in one instance with three antennas, A, B and C, arranged in a straight line and respectively radiating frequencies F, E+l5 Hz. and F+l 35 Hz. The spacing between the antenna B and antenna A has been selected in compliance with the desired sector width and the spacing between antenna C and antenna A has been chosen to be a multiple of the space between antenna B and antenna A.

With such an antenna arrangement, in a horizontal direction within said sector a coarse and fine measurement of azimuth can be performed by said receivers by a phase comparison with additionally transmitted reference signals.

If in the airplanes, it is desired to measure the elevation angle, a second, similar arrangement may be provided in the vertical direction. However, such an arrangement is too cumbersome for mobile use.

SUMMARY OF THE INVENTION It is an object of the invention to provide a sector beacon which can be utilized by airborne Tacan receivers for a determination of azimuth and elevation angles.

It is another object of the present invention to provide an improved beacon which permits a two-direction rotating radiation pattern in a predetermined sector.

Features of this invention are that the beacon has no physically moving parts and may be made relatively small and mobil.

According to the invention there is provided a beacon for radiating in a sector a radiation pattern which rotates in at least two directions at an angle with each other which comprises first means for radiating a first carrier frequency; second means for radiating a second frequency located at a first distance from said first means, which distance is determined by said first frequency and the desired width of said sector; and third meams for radiating a third frequency, the frequencies radiated by said second and third means being different from each other.

BRIEF DESCRIPTION OF THE DRAWING The above mentioned and other objects of the invention will become apparent by reference to the following description in conjunction with the accompanying drawing in which there is illustrated an antenna arrangement according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The subject invention makes use of a known principle, to wit, that a traveling field of hyperbolas are provided by two spaced antennas each of which radiates a different frequency. The produced radiation field travels at a speed which corresponds to the frequency difference between the frequency radiated by the first and second antennas. A receiver in the remote radiation field receives an amplitude modulation wave. The phase of the modulation is dependent upon the location of the receiver.

In order to provide for azimuth determination, a first antenna A radiates a carrier frequency F and a second spaced antenna B radiates a frequency, for example, F+l 35 Hz. The antennas are spaced such as to provide radiation in a predetermined sector, for example, :l 8 which spacing, for this example, is determined b the formula 5/1r-A.

In order to provi e for elevation determination, another antenna C is provided in the vertical direction above the main antenna A, preferably at a distance 5/11" A, which radiates at sas sy orl mp H1 H2 According to the above, a rnultilobe pattern is produced in a sector which gyrates in the vertical direction at aspeed corresponding to 15 Hz. and in the horizontal direction at Hz.

In order to avoid reflections at the ground, a pattern focusing is suitable at least for the radiator which enables the measuring of the elevation angle.

In order 0 carry out distance measuring as in the conventional Tacan system, the carrier frequency F, propagated by the main radiator A, may be modulated with response pulses, derived from the received interrogating pulses of the difi'erent aircraft in the same way as in the conventional Tacan system.

Conventional Tacan receivers can cooperate with such a beacon, because the beacon generates substantially the same radiation field at the receiver as a nonnal Tacan transmitter except for the fact that the field is restricted to a sector of, for example, 36. The I35 Hz. component being present in the horizontal direction for azimuth measurement and the l5 Hz. component being present in the vertical direction for elevation angle measurement.

Iclaim l. A beacon for providing, in a sector, a radiation pattern which rotates in at least two directions at an angle with each other, comprising:

first means for radiating a first carrier frequency;

second means for radiating a second frequency located at a first horizontal distance from said first means, which distance is determined by said first frequency and the desired width of said sector; and

third means for radiating a third frequency located at the second vertical distance from said first means, the frequency radiated by said second and third means being different from each other.

2. A beacon, according to claim I, wherein said second vertical distance is equal to said first horizontal distance.

3. A beacon, according to claim I, wherein said first means comprises an omnidirectional antenna.

4. A beacon, according to claim I, wherein said third frequency is higher than said first frequency by a predeter' mined frequency difference.

5. A beacon, according to claim 4, wherein said second frequency is equal to said first frequency plus a multiple of said predetermined frequency difference.

6. A beacon, according to claim I, wherein said first distance is chosen to provide an l8 sector. 

1. A beacon for providing, in a sector, a radiation pattern which rotates in at least two directions at an angle with each other, comprising: first means for radiating a first carrier frequency; second means for radiating a second frequency located at a first horizontal distance from said first means, which distance is determined by said first frequency and the desired width of said sector; and third means for radiating a third frequency located at the second vertical distance from said first means, the frequency radiated by said second and third means being different from each other.
 2. A beacon, according to claim 1, wherein said second vertical distance is equal to said first horizontal distance.
 3. A beacon, according to claim 1, wherein said first means comprises an omnidirectional antenna.
 4. A beacon, according to claim 1, wherein said third frequency is higher than said first frequency by a predetermined frequency difference.
 5. A beacon, according to claim 4, wherein said second frequency is equal to said first frequency plus a multiple of said predetermined frequency difference.
 6. A beacon, according to claim 1, wherein said first distance is chosen to provide an 18* sector. 